This invention concerns a method and a train for the highway safe transportation of a front loader implement, i.e., a back hoe or a skip loader. Such implements, for the purpose of this invention, are characterized by having a front loading scoop, hence the term "front loader" in common usage in the art. In addition, they are characterized by having a rear pair of drive wheels which are relatively large in diameter and a pair of steerable front wheels which are considerably smaller in diameter. They are four-wheeled implements in contrast to corresponding implements that travel on a pair of bands of articulated plates, i.e., on caterpillar tracks, with which latter type of implement this invention is not concerned.
In the present state of the art the front loader implement is transported on the flat bed of a trailer, preferably on a tilt bed trailer. The trailer necessarily is considerably longer and wider than the implement and has a longer wheelbase. When the implement is delivered to a worksite, the trailer is parked on the roadway, curbside, as close as possible to the worksite, and the implement is driven the rest of the way on its own power. Curbside parking space which is sometimes scarce at a worksite is tied up with the idle trailer for the duration of the job. The trailers are large, cumbersome, heavy and expensive. They are difficult to maneuver in tight places and expensive to haul. They are a traffic hazard when parked curbside overnight without lights.
In U.S. Pat. No. 2,794,565 dated Apr. 14, 1955, Lawrence S. Ratliff proposed a two-wheeled trailer for carrying the rear end of a heavy implement with caterpillar tracks while the front end, riding on an adapter chassis, is carried on the fifth wheel of a towing vehicle. The towed implement itself is a participating member of the transport train. This is the only example in the prior art of which I am aware where the implement is a participating member of the train.
In U.S. Pat. No. 3,510,016 dated May 5, 1970 William H. Wolff, et al disclosed an automobile towing trailer which has four non-steerable wheels on a chassis to which is rigidly attached a tongue on the terminus of which is a trailer coupler provided for engaging the ball of a trailer hitch on the towing vehicle. The rear wheels of the automobile are cradled in a shallow V-shaped notch in the chassis above the level of the axles. The front wheels of the automobile trail behind. In the towing mode, the front wheels remain in contact with the road.
In U.S. Pat. No. 3,653,680 issued to Donald I. Denny on Apr. 4, 1972 there is disclosed a four-wheeled trailer with tongue and trailer coupler which is adapted for the towing of an automobile. The front wheels of the trailer are provided with steering knuckles and king pins and are steerable. The rear wheels are mounted on casters free to rotate 360.degree. and they are considerably smaller in diameter. A foldable platform is interposed between the front and rear wheels of the trailer on which are carried the rear wheels of the towed automobile, leaving the front wheels thereof trailing and in contact with the road. The level of the platform is somewhat higher than the top of the front axle of the trailer. The feature of this invention is that the platform can be folded back over the front axle permitting it to be towed on two wheels instead of four when empty. A pair of removable ramps are provided, including means to hook one end of each ramp into a slot located in the trailing edge of the platform. After the automobile has been drawn up into position on the platform the ramps are manually removed and stored in a tray provided on the trailer.
The devices of the aforementioned U.S. Pat. Nos. 3,510,016 and 3,653,680 are trailers. They have all of the disadvantages that have already been attributed to trailers in the foregoing discussion.
I have found that the above mentioned disadvantages can be minimized or avoided in an implement transportation train consisting of a light, compact four wheel dolly carrying the implement with its large rear drive wheels cradled between the front and rear axles of the dolly.
In lieu of a trailer tongue I utilize the foremost projecting member of the towed implement namely, the lip of the scoop. The lip of the scoop engages a rearwardly directed lip hook provided at the fork of a Y-form towbar, the two arms of the Y being rearwardly directed under the scoop. A length of chain with terminal hook extends from the end of each of said arms, each said chain on its respective side of the Y being threaded under and behind the scoop over the lift arm on its respective side. The two chains are there tightly secured each to the other by their terminal hooks. The base of the Y-form towbar is provided at its forward-directed terminus with a conventional trailer coupler engaging the ball of a trailer hitch of a towing vehicle.
It is an object of the invention to provide an implement transportation train that is only slightly longer than the combined lengths of the implement and the towing vehicle and the overpass vertical clearance of which is only about 10 inches taller than the height of the implement when standing on the ground.
It is another object of the invention to provide an implement transportation train that is based on a four-wheeled dolly that is compact and light enough to be maneuvered into tight places like a hand truck so that said dolly can be pushed off the roadway by hand and parked while idle.
It is a third object of the invention to provide an implement transportation train in which the towed implement is carried with all four wheels above ground at a minimum clearance above road level that is consistent with good highway safety practice, thereby maintaining a low center of gravity and consequently, maximum stability on turns and deceleration.
It is a fourth object of the invention to provide optional automatically retractable ramps to permit the mounting or dismounting of the implement onto or from the dolly under its own power.
It is a fifth object of the invention to provide towbar means safely secured to the front loader scoop, whereby the towed implement becomes an actively participating member of the transportation train.
It is a sixth object of the invention to provide highway safe locking means, in the event of leakage in the hydraulic system or accidental tripping of the controls, to prevent the lowering of the scoop and towbar assembly, or of the front wheels of the implement, or of the retractable ramps while the implement is being towed.